Cobalt oxide and cuprous oxide modified gallium nitride photoelectrode for enhancing photocurrent, preparation method and application

Abstract

The invention discloses a cobalt oxide and cuprous oxide modified gallium nitride photoelectrode for enhancing photocurrent, a preparation method and application, and belongs to the technical field of electrodes. The preparation process of the photoelectrode comprises the steps that an n-GaN wafer is cut, washed and then blow-dried; the method comprises the following steps: mixing Co (NO3) 2, NaIO3 and methanol to prepare a solution A, then putting an n-GaN wafer into the solution A, and then carrying out photodeposition under ultraviolet light; washing and then drying by using nitrogen, so as to obtain an n-GaN wafer sample with Co3O4 nano particles; mixing and stirring a Na2SO3 aqueous solution and a CuSO4 aqueous solution to obtain a solution B; an n-GaN wafer sample with Co3O4 nanoparticles is suspended in the solution B for water bath heating, a NaOH solution is dropwise added, then washing is conducted, then nitrogen drying is conducted, and the cobalt oxide and cuprous oxide modified gallium nitride photoelectrode is obtained; the cobalt oxide and cuprous oxide modified gallium nitride photoelectrode is dried and shaped, and due to reasonable Co3O4 / Cu2O decoration, high response and quick response / recovery time are realized under 365nm illumination.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrodes, and in particular relates to a gallium nitride photoelectrode modified with cobalt oxide and cuprous oxide for enhancing photocurrent, a preparation method and an application thereof. Background Art

[0002] Ultraviolet detectors have attracted extensive attention in the fields of environmental monitoring, biomedicine, and intelligent optoelectronic devices due to their advantages such as energy saving, miniaturization, and high integration. With the growing demand for highly integrated and multifunctional light detection in military and civilian applications, high-performance, miniaturized, and low-dimensional UV Pds have become a new hotspot for detection. In recent years, various UV Pds based on materials such as ZnO, ZnS, NiO, and GaN have been studied. Among them, GaN is considered to be a promising candidate for the development of high-performance UV Pds due to its superior properties, such as inherent UV photosensitivity, suitable bandgap, high carrier mobility, and good chemical and thermal stability, and has broad development prospects in the field of UV light detection.

[0003] Therefore, it is urgent to find a simple way to improve the carrier mobility efficiency of GaN-based photoelectrodes. There are two main active areas in the research of carrier dynamics manipulation in semiconductor devices. On the one hand, a large number of studies focus on exploring new structures in semiconductors, whether using semiconductor heterojunctions or quantum structures such as quantum wells / dots / wires to confine or regulate carrier transport behavior. More importantly, on the other hand, how to control the interaction between the semiconductor surface and its surrounding environment, that is, controlling the interfacial physicochemical properties and interfacial carrier behavior of semiconductor materials, is crucial for further optimizing device performance or exploring new functions. In order to give these devices superior surface properties, strategic surface modification is usually carried out by loading co-catalysts (i.e., functional nanoparticles or layers). Although there are many reports on various co-catalysts, the selection of co-catalyst materials should be cautious. Inappropriate materials will rapidly increase the interface state and undesirable internal stress, while leading to the deterioration of device performance. In addition, there is still room for optimization of the thickness, morphology and crystal quality of the loaded co-catalyst to further improve the performance of the device. Precise surface modification to give the device ideal surface physicochemical properties is the key to the pursuit of PEC devices with excellent performance and new functions. Summary of the invention

[0004] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a cobalt oxide and cuprous oxide modified gallium nitride photoelectrode for enhancing photocurrent, a preparation method and an application thereof, thereby solving the problems in the prior art.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A method for preparing a gallium nitride photoelectrode modified with cobalt oxide and cuprous oxide for enhancing photocurrent comprises the following steps:

[0007] After the n-GaN wafer is cut, it is rinsed and blown dry; Co(NO3)2, NaIO3 and methanol are mixed to form solution A, and then the n-GaN wafer is placed in solution A, followed by photodeposition under ultraviolet light; after rinsing, it is dried with nitrogen to obtain an n-GaN wafer sample with Co3O4 nanoparticles;

[0008] The Na2SO3 aqueous solution and the CuSO4 aqueous solution are mixed and stirred to obtain solution B; the n-GaN wafer sample with Co3O4 nanoparticles is suspended in solution B and heated in a water bath, and a NaOH solution is added dropwise, and then rinsed and dried with nitrogen to obtain a gallium nitride photoelectrode modified with cobalt oxide and cuprous oxide;

[0009] The gallium nitride photoelectrode modified with cobalt oxide and cuprous oxide is dried and formed.

[0010] Furthermore, when preparing solution A, the molar ratio of Co(NO3)2 to NaIO3 is 1:1.

[0011] Furthermore, the volume ratio of Co(NO3)2, NaIO3 and methanol is 1:1:3.

[0012] Further, the molar ratio of Na2SO3 to CuSO4 is 1:1.

[0013] Furthermore, the concentration of the NaOH solution is 10 mg / ml.

[0014] Furthermore, the mixing and stirring rate of the Na2SO3 aqueous solution and the CuSO4 aqueous solution is 100 r / min, and the stirring time is 6 min; the water bath heating temperature is 70°C, and the heating time is 25 min.

[0015] Furthermore, the photodeposition time is 15 minutes.

[0016] Furthermore, the drying and shaping of the photoelectrode is carried out in an oven at a temperature of 80° C. for 2 hours.

[0017] A cobalt oxide and cuprous oxide modified gallium nitride photoelectrode for enhancing photocurrent is prepared using the above-mentioned method for preparing a cobalt oxide and cuprous oxide modified gallium nitride photoelectrode for enhancing photocurrent.

[0018] The above-mentioned cobalt oxide and cuprous oxide modified gallium nitride photoelectrode for enhancing photocurrent is used in photodetectors.

[0019] Beneficial effects of the present invention:

[0020] 1. The present invention has developed a highly efficient modulated UV electrode based on Co3O4 / Cu2O / n-GaN double oxide. Since the energy band of GaN is lower than that of Co3O4 / Cu2O, this structure plays an important role in accelerating the transport of photogenerated carriers. Thanks to the reasonable Co3O4 / Cu2O decoration, high response and fast response / recovery time are achieved under 365nm illumination.

[0021] 2. The sample required for the present invention is an n-GaN nanofilm, and the gallium nitride film is grown on a sapphire substrate using metal-organic chemical vapor deposition (MOCVD) technology. The structure has good stability and stable photocurrent. The effect is significantly improved after modification with Co3O4 / Cu2O, and the response is improved several times compared to the original n-type gallium nitride film. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0023] Figure 1 The present invention is a flow chart of the method for preparing a photoelectrode.

[0024] Figure 2 This is the SEM image of the sample of Example 1 in the present invention;

[0025] Figure 3 It is a comparison chart of the it at 0V at 365nm of the sample of Example 1 of the present invention and Comparative Examples 1 and 2;

[0026] Figure 4 It is a comparison diagram of the samples of Example 1 of the present invention and Comparative Example 3 at 0V at 365nm;

[0027] Figure 5 It is a comparison diagram of the samples of Example 1 of the present invention and Comparative Example 4 at 0V at 365nm;

[0028] Figure 6 It diagram of the sample of Example 1 of the present invention at different light intensities under 365nm light;

[0029] Figure 7 This is an it diagram of the sample of Example 1 in the present invention when a bias voltage is applied under 365nm light. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] A method for preparing a gallium nitride photoelectrode modified with cobalt oxide and cuprous oxide for enhancing photocurrent comprises the following steps:

[0032] S1, cutting the n-GaN (n-type gallium nitride) wafer into the required size, rinsing it with ethanol and deionized water for several times and then drying it; mixing Co(NO3)2, NaIO3 and methanol to prepare solution A, then placing the n-GaN wafer into solution A, and then photodepositing it under ultraviolet light; then rinsing it with ethanol and deionized water and then drying it with nitrogen to obtain an n-GaN wafer sample with Co3O4 nanoparticles;

[0033] S2, adding Na2SO3 aqueous solution to CuSO4 aqueous solution and stirring evenly (while stirring, use a pipette to slowly drop the Na2SO3 aqueous solution into the CuSO4 aqueous solution for multiple times) to obtain solution B; then suspending the n-GaN wafer sample with Co3O4 nanoparticles in solution B, placing it in a water bath for heating, while heating, using a dropper to drop NaOH solution into solution B, taking it out after the time is up, and then rinsing it with ethanol and deionized water and then drying it with nitrogen to obtain a gallium nitride photoelectrode modified with cobalt oxide and cuprous oxide;

[0034] S3, placing the gallium nitride photoelectrode modified with cobalt oxide and cuprous oxide into an oven for drying and shaping;

[0035] In S1, when preparing solution A, the molar ratio of Co(NO3)2 to NaIO3 is 1:1, and the volume ratio of Co(NO3)2, NaIO3 and methanol is 1:1:3.

[0036] In S1, the photodeposition time was 15 min.

[0037] In S2, the molar ratio of Na2SO3 to CuSO4 is 1:1.

[0038] In S2, the concentration of NaOH solution is 10 mg / ml.

[0039] In S2, the stirring rate is 100 r / min, the stirring time is 6 min, the water bath temperature is 70°C, and the heating time is 25 min.

[0040] In S3, the oven temperature is 80°C and the time is 2h.

[0041] In the gallium nitride photoelectrode modified with cobalt oxide and cuprous oxide, the cuprous oxide particles are 100nm to 500nm.

[0042] In the present invention, a high-speed nanostructure photoelectrode reconstruction based on n-GaN nanofilm with a reasonable Co3O4 / Cu2O structure was developed by using photodeposition followed by hydrothermal method. First, cobalt tetroxide was evenly distributed on the surface of gallium nitride photoelectrode by photodeposition, and then cuprous oxide particles were attached to the surface by hydrothermal method.

[0043] The technical scheme of the present invention is described in detail by the following examples and comparative examples;

[0044] Example 1

[0045] like Figure 1 As shown, a method for preparing a gallium nitride photoelectrode modified with cobalt oxide and cuprous oxide for enhancing photocurrent, the preparation method comprising the following steps:

[0046] S1, cutting n-GaN wafer into 1cm 2 *1cm 2 size, rinsed with ethanol and deionized water 2-3 times and then dried; 0.2 mol Co(NO3)2, 0.2 mol NaIO3 and 6 ml methanol were mixed to form solution A, and then the n-GaN wafer was placed in solution A, and then photodeposited under ultraviolet light for 15 minutes. Then, it was rinsed with ethanol and deionized water and dried with nitrogen to obtain the n-GaN wafer sample of Co3O4 nanoparticles;

[0047] S2, add 0.05mol Na2SO3 aqueous solution to 0.05mol CuSO4 aqueous solution (under the condition of stirring rate of 100r / min and stirring time of 6min, use a pipette to slowly drop the Na2SO3 aqueous solution into the Cu SO4 aqueous solution several times) to obtain solution B. Then, suspend the n-GaN wafer sample with Co3O4 nanoparticles in solution B, put it in a water bath and heat it at 70℃ for 25min. During heating, use a dropper to drop 3ml of 10mg / ml NaOH solution into solution B, then take it out, rinse it with ethanol and deionized water, and then dry it with nitrogen to obtain a gallium nitride photoelectrode modified with cobalt oxide and cuprous oxide;

[0048] S3, the gallium nitride photoelectrode modified with cobalt oxide and cuprous oxide was placed in an oven at 80°C for drying and shaping for 2 hours; its SEM image is shown in Figure 2 shown.

[0049] Comparative Example 1

[0050] The difference between Comparative Example 1 and Example 1 is that Comparative Example 1 is a common gallium nitride thin film photoelectrode, and cobalt trioxide and cuprous oxide are not attached to gallium nitride for modification.

[0051] Comparative Example 2

[0052] The difference between Comparative Example 2 and Example 1 is that in Comparative Example 2, cobalt tetroxide is attached to the gallium nitride thin film photoelectrode, but cuprous oxide is not attached for modification, and step S2 in Example 1 is not performed.

[0053] Comparative Example 3

[0054] The difference between Comparative Example 3 and Example 1 is that: 0.05 mol Na2SO3 aqueous solution is added to 0.1 mol CuSO4 aqueous solution in S2 (under the condition of stirring rate of 100 r / min and stirring time of 6 min, the Na2SO3 aqueous solution is slowly dripped into the CuSO4 aqueous solution several times with a pipette) to obtain solution B. Then, the n-GaN wafer sample with Co3O4 nanoparticles is suspended in solution B, and then placed in a water bath and heated at 70°C for 25 min. During heating, 3 ml of 10 mg / ml NaOH solution is dripped into solution B with a dropper. After the time is up, it is taken out and rinsed with ethanol and deionized water and then dried with nitrogen to obtain a gallium nitride photoelectrode modified with cobalt oxide and cuprous oxide.

[0055] Comparative Example 4

[0056] The difference between Comparative Example 4 and Example 1 is that the modified sample is not dried and shaped in S3.

[0057] Experimental testing

[0058] The performance of the gallium nitride photoelectrodes prepared in Example 1 and Comparative Examples 1-4 was tested. During the test, the current and voltage performance of the samples were tested using an electrochemical workstation 760e.

[0059] The specific test steps are as follows: Sodium sulfate solution is used as the electrolyte, the working electrode is the sample to be tested, the reference electrode is the silver / silver chloride electrode, and the counter electrode is the platinum mesh electrode. In order to simulate the light conditions of the reagent, LED lamp beads with a wavelength of 365nm are selected as the light source. The shutter is used to simulate the occurrence and shutdown of light to accurately control the time.

[0060] Figure 3 The figure shows the it comparison of 0V at 365nm for the sample of Example 1 and Comparative Examples 1 and 2. It can be seen from the figure that the current density of the n-type gallium nitride deposited with cobalt oxide and cuprous oxide is higher than that of the bare n-type gallium nitride and the n-type gallium nitride deposited with only cobalt oxide.

[0061] Figure 4The figure shows the it comparison of the sample of Example 1 and the sample of Comparative Example 3 at 0V at 365nm. It can be seen from the figure that the current density of Example 1 far exceeds the current density of Comparative Example 3, so the optimal molar ratio of Na2SO3 to CuSO4 in S2 is 1:1.

[0062] Figure 5 The figure shows the it comparison of the sample of Example 1 and the sample of Comparative Example 4 at 0V at 365nm. It can be seen from the figure that the current density of Example 1 is greater than that of Comparative Example 4, so the drying and shaping in Example 1 is an extremely important step.

[0063] Figure 6 The figure shows the IT diagram of the sample of Example 1 at different light intensities under 365nm light. It can be seen from the figure that the ratio of Example 1 fluctuates with the irradiation of light sources of different powers.

[0064] Figure 7 The figure shows the it diagram of the sample of Example 1 under 365nm light with bias voltage applied. It can be seen from the figure that Example 1 can be adjusted by bias voltage control and can be better applied in practical applications.

[0065] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0066] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. A method for preparing a gallium nitride photoelectrode modified with cobalt oxide and cuprous oxide for enhancing photocurrent, characterized in that: The following steps are involved: After the n-GaN wafer is cut, it is rinsed and blown dry; Co(NO3)2, NaIO3 and methanol are mixed to form solution A, and then the n-GaN wafer is placed in solution A, followed by photodeposition under ultraviolet light; after rinsing, it is dried with nitrogen to obtain an n-GaN wafer sample with Co3O4 nanoparticles; The Na2SO3 aqueous solution and the CuSO4 aqueous solution are mixed and stirred to obtain solution B; the n-GaN wafer sample with Co3O4 nanoparticles is suspended in solution B and heated in a water bath, and a NaOH solution is added dropwise, and then rinsed and dried with nitrogen to obtain a gallium nitride photoelectrode modified with cobalt oxide and cuprous oxide; The gallium nitride photoelectrode modified with cobalt oxide and cuprous oxide is dried and formed.

2. The method for preparing a gallium nitride photoelectrode modified with cobalt oxide and cuprous oxide for enhancing photocurrent according to claim 1, characterized in that: When preparing solution A, the molar ratio of Co(NO3)2 to NaIO3 is 1:

1.

3. The method for preparing a cobalt oxide and cuprous oxide modified gallium nitride photoelectrode for enhancing photocurrent according to claim 1, characterized in that: The volume ratio of Co(NO3)2, NaIO3 and methanol is 1:1:

3.

4. The method for preparing a gallium nitride photoelectrode modified with cobalt oxide and cuprous oxide for enhancing photocurrent according to claim 1, characterized in that: The molar ratio of Na2SO3 to CuSO4 is 1:

1.

5. The method for preparing a cobalt oxide and cuprous oxide modified gallium nitride photoelectrode for enhancing photocurrent according to claim 1, characterized in that: The concentration of the NaOH solution is 10 mg / ml.

6. The method for preparing a cobalt oxide and cuprous oxide modified gallium nitride photoelectrode for enhancing photocurrent according to claim 1, characterized in that: The mixing and stirring rate of the Na2SO3 aqueous solution and the CuSO4 aqueous solution is 100 r / min, and the stirring time is 6 min; the water bath heating temperature is 70°C, and the heating time is 25 min.

7. The method for preparing a gallium nitride photoelectrode modified with cobalt oxide and cuprous oxide for enhancing photocurrent according to claim 1, characterized in that: The photodeposition time is 15 min.

8. The method for preparing a gallium nitride photoelectrode modified with cobalt oxide and cuprous oxide for enhancing photocurrent according to claim 1, characterized in that: The drying and shaping of the photoelectrode is carried out in an oven at a temperature of 80° C. for 2 hours.

9. A gallium nitride photoelectrode modified with cobalt oxide and cuprous oxide for enhancing photocurrent, characterized in that: The photoelectrode is prepared by the method for preparing a gallium nitride photoelectrode modified with cobalt oxide and cuprous oxide for enhancing photocurrent as described in any one of claims 1 to 8.

10. Use of the gallium nitride photoelectrode modified with cobalt oxide and cuprous oxide for enhancing photocurrent as claimed in claim 9 in a photodetector.

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